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Development of additives for DME as a renewable energy
장은정(Jang, Eunjung),박천규(Park, Cheonkyu),임의순(Yim, Eui-Soon),정충섭(Jung, Choong-Sub),이봉희(Lee, Bonghee) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.05
DME is generally expected to be used as a promising clean alternative fuel to diesel fuel. DME is not natural product but a synthetic product that is produced either through the dehydration of methanol or a direct synthetic from syngas. As DME has no carbon-carbon bond in its molecular structure and is an oxygenate fuel, it's combustion essentially generates no soot. DME has such cetane number of 55~60 that it can be used as a diesel engine fuel. However, DME has low lubricity but a proven method to solve the poor lubricity is by adding lubricity improver. Therefore, the aim of this study is to develop lubricity improver of DME as a transport fuel in Korea. In this study, we investigated a possibility of fatty acid ester compounds as a candidate to improve DME lubricity as compared with current lubricity improver of diesel. We also evaluated quality characteristics, storage stability of DME with lubricity additives.
사례기반학습을 통한 유아교사의 놀이 개입유형 변화경험 탐색
장은정(Jang EunJung),유영의(Yoo YungEui) 학습자중심교과교육학회 2020 학습자중심교과교육연구 Vol.20 No.5
본 연구는 사례기반학습을 통한 유아교사의 놀이 개입유형의 변화를 알아보는 것이다. 이를 위하여 B어린이집 만 4세반 담임교사 2명을 연구 참여자로 선정하였으며, 2018년 11월부터 2019년 11월까지 사례기반학습 설계, 예비연구, 연구 참여교사 선정 및 현장 방문, 사례기반학습 실행의 4단계로 연구를 진행하였다. 연구 참여교사의 놀이 개입유형의 변화를 알아보고자 교사들이 담당하고 있는 하늘 1, 2반의 자유놀이시간을 연구자가 비참여 관찰하였고, 참여관찰, 면담, 토의노트 및 저널, 사례기반학습 토의과정을 토대로 자료를 수집하여 분석하였다. 그 결과 사례기반학습을 통한 유아교사의 놀이 개입유형 변화는 놀이를 민감하게 관찰하고 반응하는 방관자 개입유형으로 변화하기, 놀이 환경을 풍부하게 제공해주는 무대관리자 개입유형으로 변화하기, 유아의 의견을 수용하며 놀이를 공동구성하는 공동놀이자 개입유형으로 변화하기, 유아주도의 놀이가 지속될 수 있도록 놀이를 안내하는 놀이지도자 개입유형으로 변화하기, 지시보다는 효율적으로 놀이를 제안하는 감독 및 방향전환자 개입유형으로 변화하기가 나타났다. The aim of this study was to investigate early childhood teachers’ changes in play intervention type through case-based learning. To this end, two homeroom teachers of 4-year-old class at B child care center were selected as the research participants. From November 2018 to November 2019, the research was conducted in four stages: case-based learning design, preliminary research, selection of participating teachers and field visits, and implementation of case-based learning. In order to investigate the participating teachers’ changes in play involvement type, the researcher conducted a non-participatory observation. Data were collected from and analyzed based on observation notes, interviews, discussion notes and journals, and case-based learning discussion process. As a result, it was found that early childhood teachers show the following changes in play intervention type: changes to a bystander who observes and responses sensitively to play, a stage manager who provides rich play environment, a co-player who accepts the opinions of young children jointly and organizes play, a play leader who guides play so that child-initiated play is sustained, and a director and redirector who efficiently suggests play rather than giving instructions
예비유아교사의 실습 전,후의 전이에 대한 인식과 교사효능감의 변화
김현자 ( Hyunja Kim ),장은정 ( Eunjung Jang ) 대한아동복지학회 2015 아동복지연구 Vol.13 No.3
The purpose of this study is to examine the differences on the perspectives on transitions before and after practicum among pre-service early childhood teachers as they perform their routines, so that they can have confidence in their routine performance and ensure effective and reliable performance of such routines within an early childhood educational institutions. For this purpose, the researchers of this study analyzed the differences in self efficacy due to transition before and after practicum and the relationship between the interest in transition and self-efficacy as a teacher. The result of the analysis showed that, firstly, the level of interest in transition, the types of transition, the influence on children resulting from transition, and the educational effects resulting from transition were all significantly different. Second, as for the self-efficacy of the pre-service teachers, the self-efficacy level on the class strategies was significantly higher after the practicum. Third, as for the relationship between the level of interest in transition and the self-efficacy of the teachers, the self-efficacy in class strategies had a significant, static correlation. Also, there were significant static relationships between the interest level on transition and the self-efficacy in learning operations, self-efficacy in children``s participation, and the overall self-efficacy score of the teachers. Such results shed light to fact that understanding in transition before practicum can help the teachers recognize the importance of transition, which can boost the effectiveness of education and enhance self-efficacy of the teachers.
디메틸에테르에 첨가된 윤활성향상제의 윤활특성에 관한 연구
박천규(Cheonkyu Park),장은정(Eunjung Jang),정충섭(Choongsub Jung),이봉희(Bonghee Lee),나병기(Byungki Na) 한국트라이볼로지학회 2013 한국윤활학회지(윤활학회지) Vol.29 No.2
Dimethyl ether (DME) has a high cetane number that is suitable for diesel fuel. DME does not contain sulfur or nitrogen , and is an oxygenated fuel so it produces no particulate matter when combusted and is environmentally friendly. DME fuel for diesel engines show excellent material properties such as a lower volumetric heating value, lower boiling point, lower lubricity, and stronger solvent effect than light oil. This study experimentally examined a lubricity improver (LI) for dimethyl ether. A diesel LI based on biodiesel and fatty acid methyl ester was tested among DME LI candidates. The long-term storage stability and physical properties of the optimum LI for DME were determined.